Intent: To inform supervisors and users of compressed
gases of the safety procedures for working with inert, flammable, pyrophoric,
oxidizing, corrosive and toxic gases.
Information: Compressed gases have the potential to create
both chemical and mechanical hazards if handled, transported or stored
improperly. The unique hazards presented by compressed gases are dependent
upon their physical and chemical properties and the pressure of the gas
in a cylinder or delivery system.
The various types of compressed gases are described
- Nonflammable (Inert) Gas - a non reactive gas which
is not considered to be hazardous unless uncontrollably released into an
enclosed area. Inert gases may cause asphyxiation under these conditions.
Nonflammable gases should be labeled as "nonflammable gas" on a green and
- Flammable Gas - a gas which may be ignited or explode
when it accumulates between the lower and upper explosive limits for a
specific gas. Safety precautions are required when handling, using and
storing flammable gases. Flammable gases should be labeled as "flammable
gas" on a red and white placard.
- Pyrophoric Gas - a highly flammable and reactive
gas which may spontaneously burn or explode when released into air. Special
safety precautions are required when handling, using and storing pyrophoric
gases due to their reactivity. Pyrophoric gases should be labeled as "flammable
gas" on a red and white placard.
- Oxidizing Gas (e.g. oxygen) - a gas which may promote
the rapid combustion or reactivity of flammable gases or materials. These
gases should not be stored or mixed uncontrollably with flammable gases
due to their fire or explosive hazard. Oxidizing gases are labeled as "oxidizer"
on a yellow and black placard.
- Corrosive Gas - a reactive gas which may degrade
materials and cause permanent damage to body tissues upon direct contact.
Special safety precautions are required when handling, using and storing
corrosive gases. Corrosive gases are often labeled as "poison" on a white
and black placard.
- Toxic Gas - a highly poisonous gas which may be immediately
dangerous to life and health if accidentally released. Special safety precautions
are required when handling, using and storing toxic gases due to their
extreme toxicity. Toxic gases should be labeled as "poison gas" on a white
and black placard.
Standard: The following safety procedures are required when
handling, using and storing all compressed gases. Additional special safety
precautions have been developed for corrosive, pyrophoric and toxic gases.
Supervisors and users of compressed gases must
ensure the following general precautions are followed:
- Compressed gas cylinders must be clearly labeled
by a shipment tag or stenciled name at all times. Gas cylinders without
labels should not be accepted. Color coding is not a reliable means of
identification. Unidentified cylinders should be returned to the supplier.
- Compressed gas cylinders must be firmly secured at
all times. An appropriate clamp, belt or chain should be used for this
- The cylinder valve cap must be secured on the head
of a cylinder whenever it is not in use. This protects the vulnerable cylinder
valve and prevents the cylinder from becoming a dangerous projectile in
the event of an accident. Never lift a cylinder by the valve cap.
- All compressed gas cylinders should be inspected
upon their receipt. Damaged or unidentified cylinders should be immediately
returned to the supplier.
- Only CGA standard combinations of valve and fittings
should be used on compressed gas systems. This reduces the possibility
of accidentally mixing incompatible gases due to an interchange of connections.
The threads and conditions of cylinder valves, regulators and fittings
should be examined to ensure they are undamaged and correspond to one another.
- Compressed gas cylinders should only be handled,
used or stored in locations where they are not exposed to elevated temperatures,
pressures or voltages. Cylinders should not be allowed to become part of
an electrical circuit.
- Only appropriate tools should be used on gas valves
and piping systems. Improper tools may damage or exert unacceptable stresses
on a compressed gas system.
- Cylinder valves should be opened slowly to prevent
"over-stressing" compressed gas systems.
Only matched components should be used on
compressed gas systems. The materials of construction, design and installation
of individual components is very important to the safe use of gas systems.
- Rigid piping is required for the construction of
all permanent gas systems. Flexible tubing may only be used in limited
instances on nonflammable (inert) gas systems.
- All compressed gas systems must be treated after
their construction and prior to their use. Gas systems should be over-pressurized
with an inert gas to ensure their integrity. Gas systems should have a
dedicated cylinder of inert gas for purging. The house nitrogen, vacuum
and compressed gas must not be used to purge regulators or systems for
flammable, pyrophoric, oxidizing, corrosive and toxic gases.
- Employees storing, using and handling compressed
gases should understand the properties, hazards and safety precautions
by consulting their supervisors, Material Safety Data Sheets or other references.
- All flammable and oxidizing gases should be stored
separately. Flammable gases and oxygen should never be stored in close
proximity to each other or within the same ventilated gas cabinet.
- All flammable, pyrophoric, corrosive and toxic gases
should be delivered to users after working hours. Users of these gases
should arrange with building service personnel to receive and store their
gases inside secured ventilated cabinets. Cylinders of hazardous gases
should never be left in hallways, aisles or unprotected in labs without
the knowledge of the occupant.
- All gas cylinders should be secured to an appropriate
hand truck when transported through hallways or moved within a laboratory.
Gas cylinders should be transported cautiously to prevent personal injury
or damage to the cylinder.
- Gas monitoring devices should be installed in labs
where flammable, pyrophoric, corrosive and toxic gases are stored, handled
or used. Monitoring devices should be interlocked with gas systems to cut
the flow of gas if a leak is detected. Questions concerning the purchase
of gas monitoring devices or air sampling to assess potential exposure
to gas should be raised with the CfA Safety Office.
- The quantities of flammable, pyrophoric, toxic, corrosive,
and oxidizing gases should be kept to the minimum needed for an operation.
Stockpiling of gases in laboratories or shops is not permitted.
Contact: Whenever questions arise about the safe handling,
use and storage of compressed gases, contact the CfA Safety Office at 5-7478.